West Pacific/2015/11W/Archive/9
Public advisory TROPICAL STORM NANGKA PUBLIC ADVISORY NUMBER 9 WIKI-HURRICANES FORECASTING CENTER 12:00 AM JST MON JUL 06 2015 ...NANGKA IMPRESSES NOBODY... SUMMARY OF 12:00 AM JST...15:00 UTC...INFORMATION ------------------------------------------------------------------- LOCATION...11.3N, 161.7E CENTER POSITION CONFIDENCE: ZERO ABOUT 480 MI...770 KM NE OF PALIKIR, MICRONESIA MAXIMUM SUSTAINED WINDS...50 KT...60 MPH...95 KM/H MINIMUM BAROMETRIC PRESSURE...998 MB...29.47 INCHES PRESENT MOVEMENT...WNW AT 8 KT...9 MPH...15 KM/H DISCUSSION AND 48-HOUR OUTLOOK --------------------------------------------- At 12:00 am JST, the center of Tropical Storm Nangka was situated near 11.3N, 161.7E, or about 520 miles (835 kilometers) east-northeast of Palikir, Micronesia. Maximum sustained winds were 50 knots (60 mph, 95 km/h), with higher gusts. The minimum barometric pressure was 998 millibars (hPa; 29.47 inHg), and the cyclone was tracking west-northwest at 8 knots (9 mph, 15 km/h). Despite earlier indiciations that environmental conditions may not be conducive for marked strengthening, such indicators have trended towards a more conducive environment that may hint at the potential for steady if not rapid strengthening within the 48 hour timeframe. NEXT ADVISORY ------------------- Next complete advisory at 06:00 pm JST. $$ Forecaster YE Discussion TROPICAL STORM NANGKA DISCUSSION NUMBER 9 WIKI-HURRICANES FORECASTING CENTER 12:00 AM JST MON JUL 06 2015 While the center remains somewhat exposed, Nangka is at least maintaining its intensity. a 11z ASCAT pass measured a large swath of 45 knts and a 50 knt barb. The intensity remains 50 knts, but this could be conservative. Overall, Nangka still possess a small, but impressive central dense overcast near the center of circulation and a dominant spiral band to its west, with impressive transverse bands of cirrus outflow to the east. A void of deep convection exists between the core and the western rainband, allowing for a dry slot to get in. Modelling remains in good agreement in regards to the track of Nangka as the subtropical ridge to its north remains the dominant steering force. Models are also in agreement that Nangka will gain latitude more quickly the further west it traverses as a result of a weakness in the ridge induced by a progressing trough. Given that none of these parameters has changed significantly, the current WHFC track forecast is virtually an update of the last. The intensity forecast continues to increase as the forecast atmospheric conditions continue to indicate more conducive conditions. Nangka currently lies in COAMPS-analyzed 8 knot shear, and assuming Nangka does not get caught up in the outflow of Chan-hom ahead of it, conditions are expected to continue to be conducive for strengthening. Shear is expected to increase to around 20 knots at around 24 hours before dropping quite dramatically afterwards, which will be suitable for perhaps quick strengthening during that timeframe. Models have trended quite aggressively in terms of Nangka's long term intensity. Slow deepening is expectd thorugh 36 hours, then a steady state between 24 and 48 hours, then more slow intensification, before it builds an inner core. After day 3, rapid deepening is expected as the current WHFC forecast suggest that Nangka will take advantage of conducive conditions near the Mariana Islands. INIT 05/2100Z 11.4N 164.3E 50 KT 60 MPH ... NEAR MARSHALL ISLANDS 12H 06/0000Z 11.8N, 159.4W 55 KT 65 MPH 24H 06/1200Z 12.6N 157.2E 60 KT 70 MPH 36H 07/0000Z 14.0N 154.7E 60 KT 70 MPH 48H 07/1200Z 15.4N 153.0E 60 KT 70 MPH 72H 08/1200Z 18.2N 149.1W 75 KT 85 MPH 96H 09/1200Z 20.3N 144.4E 110 KT 125 MPH ... NEAR NORTHERN MARIANA ISLANDS 120H 10/1200Z 23.3N 140.3E 120 KT 140 MPH ... NEAR NORTHERN MARIANA ISLANDS $$ Forecaster YE